Answer: Fe is the element that is being oxidized (oxidation number changes from +2 to +3) while Cl is the element that is reduced (oxidation number changes from +5 to -1) in the given reaction.
Step-by-step explanation:
The question requires us to find the element that is oxidized and the one reduced in the following chemical reaction:
To solve this problem, we need to determine the oxidation number of all elements in the reactants and products sides, and then identify the elements that had their oxidation number increased (oxidized species) and decreased (reduced species).
To identify the oxidation numbers, we'll need to remember a few points:
- K is an alkali metal (part of group 1 in the periodic table), and it usually assumes the oxidation number +1;
- O usually presents oxidation number -2, except in a few specific cases;
- the anion (SO4) presents total charge -2 (in this anion, S presents oxidation number +6 and O, -2);
- H usually presents oxidation number +1.
Next, let's identify the oxidation number of all elements involved in the reaction, on both sides of the chemical equation. Since all compounds are neutral (i.e., they do not present charge), the sum of all oxidation numbers must be 0:
(note that the oxidation number of each element is indicated in red, above the respective element, while the contribution of this element to the molecule charge, considering the number of atoms, is represented in blue below the element).
In the image above, we can see that Cl has its oxidation number changing from +5 in KClO3 to -1 in KCl (highlighted in purple), while Fe has its oxidation number changing from +2 in FeSO4 to +3 in Fe2(SO4)3 (highlighted in green).
Therefore, we can say that Fe is the element that is being oxidized while Cl is the element that is reduced in the given reaction.